Mollusca "soft bodied"
Polyplacophora "many shell bearers"
Gastropoda "belly footed"
Bivalvia "two shelled"
Cephalopoda "head foot"
Chitons
Prosobranchia "gill in front"
Opisthobranchia "posterior gill"
Pulmonata "lung like"
Heterobranchia
Nudibranchs "naked gills"
Aeolids
Dorids
Squid "pertaining to pen"
Octopi "eight footed"
Nautilus "sailor"
Chitons eat plant matter with their scraping radula. They move very slowly, and their bodies are enforced with 8 shell plates for protection. They have a mantle and a foot for moving, but their heads and anuses are ill defined. They have bilateral symmetry.
Dorid nudibranchs have a gill plume on their backs, and eat sponges. They move relatively quickly on their foot, are usually bright colors, and have bilateral symmetry. Unlike other gastropods, they don't have a shell (or operculum), but have a radula to eat and rhinopores to smell with.
Aeolid nudibranchs are unique in the way that they can take unfired cnidocytes from the hydrozoans that they eat and store them in the cerata on their backs for defense. Just like their dorid counterparts, they don't move too slowly and are also brightly colored. They also have a foot to walk on, rhinopores to smell with, haven't undergone torsion, and have bilateral symmetry.
Squid are fast moving carnivores. Some species can even grow up to 50 feet long, while others will only grow 2 inches. Squid eat by catching smaller animals in their tentacles and chewing them up into fine pieces with their beak. They have a mantle, tentacles, an ink sack, highly developed eyes, and a "shell" in the form of a pen. Squid move around by using jet propulsion, and are thought to have the same level of intelligence as a dog. Squid typically live no longer than 5 years, and have bilateral symmetry.
With 8 tentacles, a beak, a mantle, 2 eyes, 3 hearts, 9 brains, and an ink sack, octopi are some of the most intelligent invertebrates in the ocean, and octopi in captivity have even been seen responding positively to music. Octopi are carnivores that can use chromatophores in their skin to change color, along with muscles that allow them to change texture. They use their beaks to eat. Unlike other mollusks, they have lost their shells through evolution, and rely on their intelligence and camouflage to survive. They move across the sea floor by crawling or using jet propulsion.
Cuttlefish "sepia"
Cuttlefish are 8 tentacled carnivorous cephalopods that can also change their color and texture. They swim using jet propulsion, but can also crawl around with their tentacles. They are also able to use ink, and have bilateral symmetry. Cuttlefish contain a cuttlebone, their devolved version of a shell, which is made out of aragonite and helps them float. Cuttlefish have 8 tentacles, a mantle, and are mainly made of soft flesh. Just like squid, cuttlefish have very short lifespans, and often only live to be 1-2 years old. Like other cephalopods, they eat by using their tentacles to bring food to their beaks.
Nautili are cephalopods that live near reefs, in the deeper waters. They only eat once a month, and can live up to 20 years. While they have 90 tentacles, nautilus have no ink and poorer vision than their familial counterparts. Unlike squid and octopus, nautilus have very large shells with many gas filled chambers for swimming. They eat by using their tentacles to pull food into their mouths.
Bivalves are mollusks that have two shells, connected at the umbo and held together with adductor muscles. Bivalves can move around by opening and closing their shells to propel themselves around, but many live in mud or underneath sand, and feed on substrate. They have bilateral symmetry, and their shells are made from calcium carbonate. Those like the oyster and abalone get their shiny, mother of pearl finish from nacre.
Ex: Geoduck clam "panope"
Pulmonata snails are land snails that have a modified vascular sac like "lung" to breath out of. Like other snails, they have undergone torsion, and move around on their large foot. They have an operculum, a mantle, and a radula that they use to eat. They eat plant matter. They also possess a pneumostome to allow them to breath, and have bilateral symmetry.
Ex: Lymonaea
Opisthobranchioids have gills in the back of their bodies. They live in the ocean, and possess most of the normal features other gastropods have (a mantle, foot, radula). Those that don't have shells have not undergone torsion, but others with shells have.
Ex: bullina linetta
Prosobranchia animals are marine snails with shells that have undergone torsion and have bilateral symmetry- this means that their anus and visceral matter are located above their heads. They have a shell and also move around on their singular foot like land snails, although they don't breath air. They eat plant matter. They also have an operculum to protect themselves when inside the shell, plus a mantle and gills, and eat with a radula.
Ex: the turban snail
Ex: The Trinchesia yamasui
Ex: The Goniobranchus splendidus